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	$174.40	12.461%	$196.132	$196.13	$196.15	$196.10
Purchase #2	$74.66	8.539%	$81.0352	$81.04	$81.05	$81.00
Purchase #3	$71.30	12.800%	$80.4264	$80.43	$80.45	$80.40
Purchase #4	$157.41	7.234%	$168.797	$168.80	$168.80	$168.80
Purchase #5	$127.70	10.385%	$140.9616	$140.96	$140.95	$141.00
Purchase #6	$142.95	13.611%	$162.4069	$162.41	$162.40	$162.40
Purchase #7	$165.37	6.593%	$176.2728	$176.27	$176.25	$176.30
7 purchase totals =	$913.79		$1,006.0319	$1,006.04	$1,006.05	$1,006.00