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	$212.27	7.105%	$227.3518	$227.35	$227.35	$227.40
Purchase #2	$196.67	6.810%	$210.0632	$210.06	$210.05	$210.10
Purchase #3	$101.25	13.342%	$114.7588	$114.76	$114.75	$114.80
Purchase #4	$79.60	8.822%	$86.6223	$86.62	$86.60	$86.60
Purchase #5	$110.46	8.218%	$119.5376	$119.54	$119.55	$119.50
Purchase #6	$115.69	10.342%	$127.6547	$127.65	$127.65	$127.70
Purchase #7	$234.92	10.276%	$259.0604	$259.06	$259.05	$259.10
7 purchase totals =	$1,050.86		$1,145.0488	$1,145.04	$1,145.00	$1,145.20