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	$144.39	4.609%	$151.0449	$151.04	$151.05	$151.00
Purchase #2	$153.49	13.620%	$174.3953	$174.40	$174.40	$174.40
Purchase #3	$216.78	12.562%	$244.0119	$244.01	$244.00	$244.00
Purchase #4	$151.60	12.615%	$170.7243	$170.72	$170.70	$170.70
Purchase #5	$94.89	3.807%	$98.5025	$98.50	$98.50	$98.50
Purchase #6	$204.76	3.140%	$211.1895	$211.19	$211.20	$211.20
Purchase #7	$54.86	12.352%	$61.6363	$61.64	$61.65	$61.60
7 purchase totals =	$1,020.77		$1,111.5047	$1,111.50	$1,111.50	$1,111.40