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	$182.69	7.318%	$196.0593	$196.06	$196.05	$196.10
Purchase #2	$37.41	6.360%	$39.7893	$39.79	$39.80	$39.80
Purchase #3	$90.65	10.257%	$99.948	$99.95	$99.95	$99.90
Purchase #4	$126.61	9.132%	$138.172	$138.17	$138.15	$138.20
Purchase #5	$66.30	10.719%	$73.4067	$73.41	$73.40	$73.40
Purchase #6	$81.77	4.236%	$85.2338	$85.23	$85.25	$85.20
Purchase #7	$222.62	11.107%	$247.3464	$247.35	$247.35	$247.30
7 purchase totals =	$808.05		$879.9555	$879.96	$879.95	$879.90