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	$141.74	5.826%	$149.9978	$150.00	$150.00	$150.00
Purchase #2	$42.64	7.789%	$45.9612	$45.96	$45.95	$46.00
Purchase #3	$232.75	3.250%	$240.3144	$240.31	$240.30	$240.30
Purchase #4	$110.61	7.581%	$118.9953	$119.00	$119.00	$119.00
Purchase #5	$200.32	5.765%	$211.8684	$211.87	$211.85	$211.90
Purchase #6	$189.77	3.404%	$196.2298	$196.23	$196.25	$196.20
Purchase #7	$147.52	5.836%	$156.1293	$156.13	$156.15	$156.10
7 purchase totals =	$1,065.35		$1,119.4962	$1,119.50	$1,119.50	$1,119.50