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	$191.86	13.657%	$218.0623	$218.06	$218.05	$218.10
Purchase #2	$232.46	13.280%	$263.3307	$263.33	$263.35	$263.30
Purchase #3	$72.83	13.653%	$82.7735	$82.77	$82.75	$82.80
Purchase #4	$31.51	12.265%	$35.3747	$35.37	$35.35	$35.40
Purchase #5	$50.90	5.138%	$53.5152	$53.52	$53.50	$53.50
Purchase #6	$174.61	8.872%	$190.1014	$190.10	$190.10	$190.10
Purchase #7	$181.61	11.323%	$202.1737	$202.17	$202.15	$202.20
7 purchase totals =	$935.78		$1,045.3315	$1,045.32	$1,045.25	$1,045.40