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	$212.86	4.211%	$221.8235	$221.82	$221.80	$221.80
Purchase #2	$46.83	11.444%	$52.1892	$52.19	$52.20	$52.20
Purchase #3	$238.53	6.299%	$253.555	$253.56	$253.55	$253.60
Purchase #4	$64.72	3.665%	$67.092	$67.09	$67.10	$67.10
Purchase #5	$155.60	11.524%	$173.5313	$173.53	$173.55	$173.50
Purchase #6	$243.89	8.384%	$264.3377	$264.34	$264.35	$264.30
Purchase #7	$155.36	7.555%	$167.0974	$167.10	$167.10	$167.10
7 purchase totals =	$1,117.79		$1,199.6261	$1,199.63	$1,199.65	$1,199.60