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	$184.88	3.524%	$191.3952	$191.40	$191.40	$191.40
Purchase #2	$57.81	9.109%	$63.0759	$63.08	$63.10	$63.10
Purchase #3	$184.82	6.102%	$196.0977	$196.10	$196.10	$196.10
Purchase #4	$165.61	13.553%	$188.0551	$188.06	$188.05	$188.10
Purchase #5	$96.87	11.618%	$108.1244	$108.12	$108.10	$108.10
Purchase #6	$42.97	6.586%	$45.8	$45.80	$45.80	$45.80
Purchase #7	$138.61	13.266%	$156.998	$157.00	$157.00	$157.00
7 purchase totals =	$871.57		$949.5463	$949.56	$949.55	$949.60