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	$219.68	3.761%	$227.9422	$227.94	$227.95	$227.90
Purchase #2	$150.74	3.866%	$156.5676	$156.57	$156.55	$156.60
Purchase #3	$50.74	6.156%	$53.8636	$53.86	$53.85	$53.90
Purchase #4	$168.64	11.582%	$188.1719	$188.17	$188.15	$188.20
Purchase #5	$120.43	5.471%	$127.0187	$127.02	$127.00	$127.00
Purchase #6	$89.35	7.459%	$96.0146	$96.01	$96.00	$96.00
Purchase #7	$74.81	5.277%	$78.7577	$78.76	$78.75	$78.80
7 purchase totals =	$874.39		$928.3363	$928.33	$928.25	$928.40