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	$195.72	3.345%	$202.2668	$202.27	$202.25	$202.30
Purchase #2	$82.77	12.187%	$92.8572	$92.86	$92.85	$92.90
Purchase #3	$65.41	9.485%	$71.6141	$71.61	$71.60	$71.60
Purchase #4	$221.78	9.840%	$243.6032	$243.60	$243.60	$243.60
Purchase #5	$68.28	12.115%	$76.5521	$76.55	$76.55	$76.60
Purchase #6	$32.77	13.845%	$37.307	$37.31	$37.30	$37.30
Purchase #7	$215.31	12.192%	$241.5606	$241.56	$241.55	$241.60
7 purchase totals =	$882.04		$965.7610	$965.76	$965.70	$965.90