Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$219.46	5.375%	$231.256	$231.26	$231.25	$231.30
Purchase #2	$99.82	12.614%	$112.4113	$112.41	$112.40	$112.40
Purchase #3	$174.71	12.679%	$196.8615	$196.86	$196.85	$196.90
Purchase #4	$249.42	8.578%	$270.8152	$270.82	$270.80	$270.80
Purchase #5	$234.89	8.116%	$253.9537	$253.95	$253.95	$254.00
Purchase #6	$135.31	10.498%	$149.5148	$149.51	$149.50	$149.50
Purchase #7	$139.94	13.279%	$158.5226	$158.52	$158.50	$158.50
7 purchase totals =	$1,253.55		$1,373.3351	$1,373.33	$1,373.25	$1,373.40