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	$188.60	4.315%	$196.7381	$196.74	$196.75	$196.70
Purchase #2	$85.43	13.198%	$96.7051	$96.71	$96.70	$96.70
Purchase #3	$199.73	7.806%	$215.3209	$215.32	$215.30	$215.30
Purchase #4	$87.97	13.135%	$99.5249	$99.52	$99.50	$99.50
Purchase #5	$175.58	10.503%	$194.0212	$194.02	$194.00	$194.00
Purchase #6	$194.75	7.607%	$209.5646	$209.56	$209.55	$209.60
Purchase #7	$144.93	6.649%	$154.5664	$154.57	$154.55	$154.60
7 purchase totals =	$1,076.99		$1,166.4412	$1,166.44	$1,166.35	$1,166.40