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	$242.90	9.157%	$265.1424	$265.14	$265.15	$265.10
Purchase #2	$65.34	10.147%	$71.97	$71.97	$71.95	$72.00
Purchase #3	$145.44	4.775%	$152.3848	$152.38	$152.40	$152.40
Purchase #4	$87.70	4.114%	$91.308	$91.31	$91.30	$91.30
Purchase #5	$173.63	13.229%	$196.5995	$196.60	$196.60	$196.60
Purchase #6	$185.87	10.866%	$206.0666	$206.07	$206.05	$206.10
Purchase #7	$132.89	10.814%	$147.2607	$147.26	$147.25	$147.30
7 purchase totals =	$1,033.77		$1,130.7320	$1,130.73	$1,130.70	$1,130.80