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	$99.54	10.165%	$109.6582	$109.66	$109.65	$109.70
Purchase #2	$152.73	3.287%	$157.7502	$157.75	$157.75	$157.80
Purchase #3	$53.89	4.845%	$56.501	$56.50	$56.50	$56.50
Purchase #4	$151.72	7.358%	$162.8836	$162.88	$162.90	$162.90
Purchase #5	$243.47	4.343%	$254.0439	$254.04	$254.05	$254.00
Purchase #6	$225.51	7.699%	$242.872	$242.87	$242.85	$242.90
Purchase #7	$105.70	7.525%	$113.6539	$113.65	$113.65	$113.70
7 purchase totals =	$1,032.56		$1,097.3628	$1,097.35	$1,097.35	$1,097.50