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	$192.83	9.866%	$211.8546	$211.85	$211.85	$211.90
Purchase #2	$247.39	10.401%	$273.121	$273.12	$273.10	$273.10
Purchase #3	$171.66	8.137%	$185.628	$185.63	$185.65	$185.60
Purchase #4	$58.84	3.431%	$60.8588	$60.86	$60.85	$60.90
Purchase #5	$133.56	13.394%	$151.449	$151.45	$151.45	$151.40
Purchase #6	$175.92	12.793%	$198.4254	$198.43	$198.45	$198.40
Purchase #7	$111.89	4.112%	$116.4909	$116.49	$116.50	$116.50
7 purchase totals =	$1,092.09		$1,197.8277	$1,197.83	$1,197.85	$1,197.80