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	$164.38	5.482%	$173.3913	$173.39	$173.40	$173.40
Purchase #2	$197.27	9.742%	$216.488	$216.49	$216.50	$216.50
Purchase #3	$184.95	3.317%	$191.0848	$191.08	$191.10	$191.10
Purchase #4	$231.56	5.294%	$243.8188	$243.82	$243.80	$243.80
Purchase #5	$40.82	5.454%	$43.0463	$43.05	$43.05	$43.00
Purchase #6	$171.88	5.102%	$180.6493	$180.65	$180.65	$180.60
Purchase #7	$41.68	12.199%	$46.7645	$46.76	$46.75	$46.80
7 purchase totals =	$1,032.54		$1,095.2430	$1,095.24	$1,095.25	$1,095.20